New functions for Part model
New functions for Part model

- is_bom_valid() - Tests if bom checksums match
- check_bom() function to mark the BOM as valid

SchrodingersGat/InvenTree,SchrodingersGat/InvenTree,inventree/InvenTree,inventree/InvenTree,inventree/InvenTree,inventree/InvenTree,SchrodingersGat/InvenTree,SchrodingersGat/InvenTree